The zebrafish, Danio rerior, has recently emerged as an important model for studying early vertebrate ontogeny, the number of developmental mutants identified via mutagenesis screens currently exceeding 2,000. Several of the genes responsible for these mutant phenotypes will likely have human counterparts which may give rise to corresponding aberrant conditions and birth defects. In order to study the underlying biology o these developmental processes either singly or in tot or in toto, it is a conditio sine qua non that these genes be molecularly "cloned". While to date a few such zebrafish genes have been cloned, the genomics infrastructure for initiating positional cloning projects and chromosomal walks is not well established, particularly with regard to large-insert cloning reagents. Many developmental biologists remain daunted by the burden of initiating such projects afresh. Additionally, since the time and financial resources required for this commitment are considerable, the biologist is distanced further from addressing critical and meaningful questions germane to a more in-depth understanding of the developmental biology. As recommended by the trans-NIH zebrafish coordinating committee, better genomics infrastructure for facilitating the identification of mutant genes is a central imperative for the community. Thus, the overriding objective of this proposal is to generate and maintain large-insert genomics resources that are readily accessible to the zebrafish community in order to more expeditiously clone developmentally relevant genes. This will be accomplished by constructed improved BAC and PAC libraries from inbred strains of zebrafish, generating pools of these libraries as well as from an existing large-insert library, distributing genomics reagents (along with appropriate user-friendly protocols) to the community, and serving as a centralized repository for genome resources, information and expertise. Data generated with respect to these resources will be stored in ZFIN, and proper scripts for their entry will be developed. Dissemination of resources, both physical and virtual, will encourage, multi-tiered, inter-programmatic cooperation within the community. In addition, the libraries so generated will be an integral component for future large-scale physical mapping and sequencing of the zebrafish genome, as well as functional genomics experiments.